Simply loading the NTSC file onto the timeline and then rendering it with a PAL template should work well. It handles all the conversions necessary automatically.
Except, be sure the project is PAL before loading the NTSC media, and then pan/crop to match the aspect ratio. After spending 2 weeks in PAL land teaching with only PAL, I learned a lot about Vegas at the PAL level. You'll lose little in the conversion. Some colors will soften, but nothing significant.